The 2188 workings are essentially the same as your 1680 with the exception of the cab/electronics and longer cleaning shoe. So as far as the wear on the machine goes you should have a good handle on it. Just make sure the electronics/hyd all work, 97's were not known for trouble in that area.
ours is the long shoe is the 2188 longer is the electronics/hyd a big enough problem to stay away from also they are replacing the ears on the rotor and the veins and the concaves (concaves with used) is that normal at 1500hrs they said it was primarily a soybean combine. thanks again